In general, in image formation devices using electrophotographic printing methods such as copying machines, printers, facsimiles, etc., rollers provided with electrical conductivity are used such as transfer rollers, developing rollers, toner supply rollers, electrification rollers, cleaning rollers, intermediate transfer rollers, belt driving rollers, etc. in each step of the image formation.
As such a roller member, in order to obtain desired surface roughness, electrical conductivity and hardness etc., conventionally used is one that are provided with a layer or layers provided on the outer periphery of a basic structure which is a structure constituted by shaft on which an elastic layer is formed, the elastic layer being composed of rubber, polymeric elastomer, polymer foam. etc. which was given electrical conductivity by the combination of a conductive agent.
As a technology relating to the improvement of the conductive roller, for example, Patent document 1 describes a conductive roller having a core metal, a substrate provided on the surface thereof and a filler layer provided on the cylindrical surface of the substrate which is composed of conductive flexible polyurethane foam, wherein a release opening for a bubble of conductive flexible polyurethane foam in the cylindrical surface is blocked by the filler layer.